Today's release of the World Conservation Union (IUCN) updated 2003 Red List of Threatened Species shows that the flagship species of the storied river in Southeast Asia is classified as Critically Endangered, its numbers further reduced from its classification as Endangered in the previous IUCN Red List. The Switzerland-based organization's members from 140 countries include some 70 states, 100 government agencies, and 750 NGOs.

"P. gigasthe largest freshwater fish according to the Guinness Book of Recordsis now very rare in northeast Thailand, southern Lao PDR, and Vietnam," said IUCN in a news release issued today. "Only 11 and eight fish were caught in 2001 and 2002 respectively. In 2003, fishers captured six giant catfish in Cambodia, all of which were released as part of the Mekong Fish Conservation Project."

The disappearance of the Mekong giant catfish is a sign of the slow decline of environmental conditions throughout the river. Like many species in the Mekong, the giant catfish needs great stretches of the river to migrate seasonallyand it must have specific water quality and flow to move through its lifecycles of spawning, eating, and breeding.

But the Mekong is under threat from human development. Millions of people along its banks in Laos, Cambodia, and Vietnam rely on the river for their livelihood. Growing pressure by fisheries, damming, and habitat destruction threaten not only the giant catfish and other species that live in the riverbut also the welfare of the people who depend on the Mekong.

National Geographic News spoke to Zeb Hogan of the Mekong Fish Conservation Project about the plight of the Mekong and its giant catfish. Hogan has received funding from the National Geographic Society to research and promote the conservation of the fish (see sidebar).

The Mekong giant catfish has just been listed by the IUCN as Critically Endangered. What does this mean and just how bad is it for this fish?

The Mekong giant catfish has been re-listed as Critically Endangered because we have new information which indicates that populations of the fish have declined significantly over the past several years. A hundred years ago, the Mekong giant catfish was found throughout the Mekong River Basin and reports indicate that fishermen harvested hundreds, or possibly even thousands, of fish per year. In recent times, the catch has dropped to between five and ten fish per year and the species has disappeared from almost all areas where it once occurred.

Why is the Mekong giant catfish so special, so important to keep it in the wild?

The Mekong giant catfish is one of the largest and most vulnerable freshwater species in the world. It is also a culturally important and charismatic species. The Mekong giant catfish symbolizes the ecological integrity of the Mekong River, because the species is so vulnerable to fishing pressure and changes in the river environment. Thus, the status of the species is one indicator of the health of the river. The recovery of the species is an important part of the sustainable management of the Mekong River Basin.